Abstract: The invention notably relates to a method for controlling depth of a seismic cable having ballasts spaced apart along its length and providing a neutral buoyancy to the seismic cable, the seismic cable being adapted for midwater data acquisition, each end of the seismic cable being connected to a respective surface autonomous vessel exerting tension on the cable through a respective lead-in cable having a negative buoyancy, the method comprising, with respect to a target depth, varying the deployed length of each lead-in cable and/or the tension exerted on the cable by each respective surface autonomous vessel. This provides an improved solution for seismic prospecting in aquatic mediums.

Abstract: The invention in particular relates to a method for controlling the horizontal position of a seismic cable adapted for acquiring seismic data midwater. The method comprises, based on a deviation observed between the position of the seismic cable and a setpoint horizontal position, a correction of the position of the seismic cable through an adjustment of the forces respectively exerted by lead-in cables on the ends of the seismic cable, the exerted forces simultaneously and each having an axial component and a lateral component relative to the seismic cable at at least one moment of the correction. This allows an easy to implement and relatively precise control of the horizontal position of a seismic cable adapted for acquiring seismic data midwater and kept stationary or quasi-stationary during the data acquisition.

Abstract: The invention notably relates to a water surface autonomous vessel having a hull and configured to be connected, through a lead-in cable having a negative buoyancy, to an end of a seismic cable having a neutral buoyancy and adapted for midwater data acquisition, wherein the water surface autonomous vessel comprises a winch for varying the deployed length of the lead-in cable, and the hull of the autonomous vessel forms a conduct at the back of the autonomous vessel in the direction of deployment of the lead-in cable. This provides an improved solution for seismic prospecting in aquatic mediums.

Abstract: The invention in particular relates to a method for controlling the horizontal position of a seismic cable adapted for acquiring seismic data midwater. The method comprises, based on a deviation observed between the position of the seismic cable and a setpoint horizontal position, a correction of the position of the seismic cable through an adjustment of the forces respectively exerted by lead-in cables on the ends of the seismic cable, the exerted forces simultaneously and each having an axial component and a lateral component relative to the seismic cable at at least one moment of the correction. This allows an easy to implement and relatively precise control of the horizontal position of a seismic cable adapted for acquiring seismic data midwater and kept stationary or quasi-stationary during the data acquisition.

Abstract: The invention notably relates to a method for controlling depth of a seismic cable having ballasts spaced apart along its length and providing a neutral buoyancy to the seismic cable, the seismic cable being adapted for midwater data acquisition, each end of the seismic cable being connected to a respective surface autonomous vessel exerting tension on the cable through a respective lead-in cable having a negative buoyancy, the method comprising, with respect to a target depth, varying the deployed length of each lead-in cable and/or the tension exerted on the cable by each respective surface autonomous vessel. This provides an improved solution for seismic prospecting in aquatic mediums.

Abstract: A method for seismic prospecting in an aquatic medium using a device having at least one seismic cable provided with sensors and at least one moving seismic source. The method includes the following steps: 1) moving the cable in the water using two drones each placed at one end of the cable and which maintain tension in the cable, the movement of the cable minimizing the deviation of the cable with respect to a desired route in the terrestrial reference frame where the movement of the cable is also being restricted by a maximum track curvature value in the water, and, at the same time; and 2) moving the seismic source in a reference frame connected to the cable, emitting waves via the seismic source, and sensing reflections of the waves by the cable.

Abstract: A system for aquatic seismic prospecting includes at least one submerged mobile seismic source for creating a disturbance transmitted through an aquatic medium in the form of waves and at least one cable having a plurality of sensors for collecting waves transmitted by the at least one submerged mobile seismic source and reflected from geological layers beneath the aquatic medium. The system also includes means for detecting and measuring the reflected waves and means for placing the at least one cable under tension, the tensioning means attached to ends of the at least one cable and the tensioning means keeping the at least one cable in a pseudo-stationary position. These is also means for holding the at least one cable at a substantially constant depth greater than approximately 5 meters.

Abstract: A method is proposed for acquiring seismic data relative to an area of the subsoil, wherein at least one seismic source is moved and seismic waves are emitted in successive shooting positions of the source so as to illuminate said area of the subsoil, and the signals resulting from this emissions are picked up using a set of cables having a substantially zero buoyancy and provided with receivers. The cables have a substantially zero speed or a speed substantially slower than the source in the terrestrial reference frame. And said successive shot positions are determined as a function of the position of the receivers relative to the terrestrial reference frame to optimize at least one quality criterion relating to the set of seismic signals acquired by the receivers in respect of said area. Such a method enables improved seismic data acquisition.

Abstract: A seismic streamer incorporates apparatus for controlling its depth of immersion for modifying and maintaining its degree of immersion, wherein, the streamer being designed for stationary use and including a power supply network, the immersion control apparatus comprises a plurality of variable buoyancy ballasts connected to the power supply network of the streamer and installed at regular intervals along the seismic streamer and each associated with a microcontroller for at least controlling buoyancy of the corresponding ballast, a plurality of pressure sensors also installed at regular intervals along the streamer, at least one receiver for one or more desired value instructions, a bus for distributing the one or more desired value instructions to the ballasts, the microcontroller associated with a given ballasts being adapted to receive at least signals originating from at least one pressure sensor located in the proximity of the ballast and instruction signals originating from the receiver for instruction